Polymer thickened lubricating greases and their preparation are known in the art. In U.S. Pat. No. 3,392,119, a grease is described comprising a white mineral oil that has been thickened by means of a copolymer of ethylene and a homopolymer of polypropylene. In U.S. Pat. No. 3,850,828, a lubricating grease composition has been described which is thickened with a polymeric mixture comprising a polyethylene and an atactic polypropylene. In EP 0700986 A2, a polymeric thickener for lubricating grease compositions is disclosed comprising containing a mixture of copolymers or homopolymers of polypropylene having a high molecular weight and a copolymer or homopolymer of propylene having a low molecular weight. Further, In EP 0942063, a lubricating grease composition is described comprising at least one polyolefin component, at least one base oil component and at least one rubber component.
These known polymer thickened lubricating grease compositions still leave room for improvement in respect of friction reduction in various bearing applications.